Reaming cast iron question

Since carbon fibre composites only seem to have about half the Young's modulus of steel, they would be rather bendy. Lightness wouldn't be much of an advantage except, maybe, in the International Space Station (Images of Dean, Smith and Grace with beryllium bed :-).

Tungsten is twice as stiff as steel and is used to make tool holders for lathes using ceramic inserts.... Think 75hp going into an 8" diameter super alloy workpiece. Tungsten carbide is nearly 3.5 times as stiff as steel and is used for boring pars.

Hey grandma, do you know how to suck eggs?

Mark Rand RTFM

Reply to
Mark Rand
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In article , Mark Rand writes

Doh - I forgot that carbon fibre is only stiffer weight-for-weight.

Not my boring bars - mine are mild steel with tungsten carbide tips, and flex like anything - teach me to cheapskate with Chinese stuff !

A set of Arrand bars is on my Christmas list - anyone here got any experience of them ?

I've been trying to stop her doing that for years - makes a terrible mess of her false teeth...

Reply to
Bob Unitt

All grades of steel have about the same Young's Modulus. Composition and heat treatment will affect the tensile strength and hardness but the Young's Modulus stays resolutely the same. Mild steel is therefore as good a material for the shank of a boring bar as the best high alloy heat treated steel. I know, it bugs me too and doesn't seem totally logical but it appears to be the case.

-- Dave Baker

Reply to
Dave Baker

In article , Dave Baker writes

But Tungsten would be better ?

Reply to
Bob Unitt

Of course. It has a higher Young's Modulus.

-- Dave Baker

Reply to
Dave Baker

Yep - you are right. Composition of the alloy has only a very minor effect on the Youngs modulus, and the state of hardness none at all.

The state of hardness/temper affects only the point at which you reach elastic limit & what happens when you do - deformation vs the material fracturing.

Regards, Tony

Reply to
Tony Jeffree

This is not an insignificant consideration. I have a home made 1/2" 10tpi ACME tap that has an interesting corkscrew section in the bit that didn't get hot enough when I was hardening it.

Mark Rand RTFM

Reply to
Mark Rand

These particular tools were not only tungsten, they were about 3" tall by 1/4" wide to hold a 3/8" diameter round ceramic bit. Seriously stiff. IIRC they are used to cut the slots between blade disks on aviation gas turbine rotors.

Mark Rand RTFM

Reply to
Mark Rand

Shhhh!

Keep schtum and patent it. No one will ever know.

Reply to
Nigel Eaton

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